This invention relates to terminal connection of electrical conductors and particularly directed to an insertable cage assembly device for use in connecting electrical conductors in a terminal block.
In the past, numerous devices have been proposed for securing electrical conductors in a terminal block. Clearly the most pertinent is U.S. Pat. No. 3,246,283, issued Apr. 12, 1966 to Paul Huska, the inventor in the present case. However, the '283 patent discloses a device wherein securing of the electrical conductor (or conductors) within the terminal block is dependent upon the craftsman turning a screw to open the terminal block to receive the conductor and, subsequently, reversing the screw to clamp the conductor end, while holding the conductor end in the desired position within the terminal block. The above is an over simplification of the work to be performed.
Terminal blocks are usually used to secure electrical or electronic conductors in communication systems, instrumentation systems and control systems from the simple to the most complex. It is obvious, therefore, that the highest degree of reliability be secured for conductor terminations. The integrity of any system is greatly contingent upon workmanship and adequacy of the terminal blocks.
Furthermore, mechanical motion, vibration, temperature variations, cold flow characteristics of materials used, realignment of conductor strands, especially where more than one conductor occupies the same "clamp space" affect proper connection. Under such conditions the reliability of the electrical/electronic systems noted above is of great concern. Indeed, life, property and equipment may be in jeopardy.
Moreover circuitry could be adversely affected due to changes in resistance values of a given circuit. Especially critical, is the problem of a conductor withdrawing from a terminal block because of the loosening actions described above. This occurs in many instances where conductors are installed under tension. Hence, when the force is great enough, a conductor will pull out and away from its terminal block. These kinds of occurrences, and they are frequent, can be disastrous. The present invention overcomes these problems and provides improved means for attaching the terminal block to a mounting rail.
A search in the U.S. Patent Office has revealed various others patents which are generally related to the present invention. The most pertinent patents found in the search are the following:
______________________________________ Patent No. Inventor Issue Date ______________________________________ 1,439,657 R. Zollner Dec. 19, 1922 1,642,042 J. L. Polk Sept. 13, 1927 3,001,173 A. H. Swengel Sept. 19, 1961 2,166,346 H. A. Douglas July 18, 1939 3,152,855 E. C. Crowther Oct. 13, 1964 3,304,392 E. W. Isler Feb. 14, 1967 3,915,545 Y. Saito Oct. 28, 1975 3,989,345 C. P. DeVito Nov. 2, 1976 4,476,400 T. Jo et al Oct. 9, 1984 4,643,513 C. B. Martin Feb. 17, 1987 ______________________________________
The Isler, Saito, Swengel, Martin and Zollner patents each suggests the use of spring clamping means. However, none of these provides a quickly releasable means for locking the clamping means in a fully open position to facilitate insertion of a conductor therein. The patents of Polk, Douglas, Crowther, DeVito and Jo are generally related to the subject matter of the present invention, but are believed to be less pertinent than those patents referred to above.